Abstract: A rubber composition for heavy-load tires including an aromatic vinyl-conjugated diene copolymer having a glass transition temperature (Tg) of ?50° C. or lower and having a functional group interactive with silica; and silica.

Abstract: For a tire excellent in strength, low-heat buildup property, wet grip property, and driveability, and a rubber composition and a conjugated diene rubber for the tire, a conjugated diene rubber of the present invention includes 5 wt % or more of a structure that 3 or more conjugated diene polymer chains are bound via a denaturing agent, obtained by reaction of each chain and the agent, each chain being that at least one of terminals is an isoprene block having 70 wt % or more of an isoprene monomer unit, and the other is an active terminal, the agent having, per molecule, at least one of an epoxy group(s) and a hydrocarbyloxysilyl group(s), and being that a total number of the epoxy group(s) and hydrocarbyloxy groups in the hydrocarbyloxysilyl group(s) per molecule is 3 or more.

Abstract: A conjugated diene rubber of the present invention is prepared from conjugated diene polymer chains, wherein the conjugated diene polymer chains each has an active end at one end and an isoprene block at least at the other end, the isoprene block contains 70 wt % or more isoprene monomer units, and the active ends of at least part of the conjugated diene polymer chains are modified with a compound having a >C?O group as a functional group. This provides (i) a tire that has an excellent strength, excellent low-heat buildup property, and excellent wet grip property and (ii) a rubber composition and a conjugated diene rubber that are suitably used to produce the tire.

Abstract: A conjugated diene rubber of the present invention is prepared from conjugated diene polymer chains, wherein the conjugated diene polymer chains each has an active end at one end and an isoprene block at least at the other end, the isoprene block contains 70 wt % or more isoprene monomer units, and the active ends of at least part of the conjugated diene polymer chains are modified with a compound having a >C?O group as a functional group. This provides (i) a tire that has an excellent strength, excellent low-heat buildup property, and excellent wet grip property and (ii) a rubber composition and a conjugated diene rubber that are suitably used to produce the tire.

Abstract: For a tire excellent in strength, low-heat buildup property, wet grip property, and driveability, and a rubber composition and a conjugated diene rubber for the tire, a conjugated diene rubber of the present invention includes 5 wt % or more of a structure that 3 or more conjugated diene polymer chains are bound via a denaturing agent, obtained by reaction of each chain and the agent, each chain being that at least one of terminals is an isoprene block having 70 wt % or more of an isoprene monomer unit, and the other is an active terminal, the agent having, per molecule, at least one of an epoxy group(s) and a hydrocarbyloxysilyl group(s), and being that a total number of the epoxy group(s) and hydrocarbyloxy groups in the hydrocarbyloxysilyl group(s) per molecule is 3 or more.

Abstract: A conjugated diene rubber composition comprising (A) 5-95 wt. % of a conjugated diene rubber having a structure such that at least three conjugated diene polymer chains are bonded together through a specific polyorganosiloxane having groups containing alkylene glycol repeating units and (B) 95-5 wt. % of a conjugated diene rubber having reacted with a compound having in the molecule a functional group selected from >C?O, >C?S, amino, imino, epoxy, pyridyl, alkoxyl and halogeno. This rubber composition gives, when silica is incorporated therein, a vulcanizable rubber composition having good processability and giving a rubber vulcanizate exhibiting sufficiently reduced heat build up, and having good wet-grip property and good abrasion resistance.

Abstract: Disclosed are silica-filled rubber granules comprised of a cocoagulation product of rubber and silica, which are extremely less powdery and excellent in handling and kneading, as well as an industrially advantageous process for producing same. The silica-filled rubber granules of the present invention are dried granules of a cocoagulation product of rubber and silica particles, which are characterized in that an average particle diameter (D50) in terms of the sieve analysis is 300˜3000 ?m and the weight ratio of the granules within the range of D50±(D50×0.5) is at least 50% by weight. The silica-filled rubber granules are produced by supplying a cake of a cocoagulation product of silica and rubber having a water content of 40˜80% by weight to a drier provided with an indirect-heating type container having stirring wing blades, and then drying the cake while stirring it with the stirring wing blade.

Abstract: The present invention is to provide a diene rubber composition and a cross-linked diene rubber thereof excellent in tensile strength, wear resistance and processability, keeping compatibility of both good fuel efficiency and high gripping property, and a production method thereof. What is characterized in the composition is that the composition is comprised of 100 parts by weight of a diene rubber having a molecular weight distribution expressed in terms of the ratio of the weight-average molecular weight to the number-average molecular weight of 1.1 to 30, 20 to 200 parts by weight of silica and a cationic polymer, and that a toluene-insoluble rubber content per gram of the silica within the range from 0.2 to 1 g, and diene cross-linked rubber thereof.

Abstract: A conjugated diene rubber composition comprising (A) 5-95 wt. % of a conjugated diene rubber having a structure such that at least three conjugated diene polymer chains are bonded together through a specific polyorganosiloxane having groups containing alkylene glycol repeating units and (B) 95-5 wt. % of a conjugated diene rubber having reacted with a compound having in the molecule a functional group selected from >C?O, >C?S, amino, imino, epoxy, pyridyl, alkoxyl and halogeno. This rubber composition gives, when silica is incorporated therein, a vulcanizable rubber composition having good processability and giving a rubber vulcanizate exhibiting sufficiently reduced heat build up, and having good wet-grip property and good abrasion resistance.

Abstract: A silica-containing conjugated diene rubber composition comprising a conjugated diene rubber-silica mixture (A) containing at least 30 wt % of toluene insoluble components obtainable by co-coagulating an aqueous dispersion or solution of conjugated diene rubber (a) having a glass transition temperature of ?120 to 0° C. with an aqueous dispersion of silica, blended with a conjugated diene rubber (b) having a glass transition temperature such that the difference in absolute value between the glass transition temperature of rubber (b) and that of rubber (a) is 3 to 100° C. According to the invention, it is possible to provide a rubber composition having highly balanced fuel efficiency, wet grip performance, mechanical strength, wear resistance and low temperature brittleness resistance; and suitably used for tire treads.

Abstract: A conjugated diene rubber obtained by a process wherein active conjugated diene polymer chains each having an active metal at a polymer chain terminal, which have been obtained by polymerizing a conjugated diene monomer alone, or a conjugated diene monomer and an aromatic vinyl monomer with the aid of an organic active metal in an inert solvent, are allowed to react with a specific polyorganosiloxane capable of reacting with the active metal bonded to the polymer chain terminal. The conjugated diene rubber contains at least 5% by weight of a structure comprising at least three conjugated diene polymer chains bonded through a polyorganosiloxane. The conjugated diene rubber gives, when silica is incorporated therein, a rubber composition having good processability and giving a crosslinked rubber having reduced heat build-up, good wet grip performance and good abrasion resistance.

Abstract: The present invention is to provide a diene rubber composition and a cross-linked diene rubber thereof excellent in tensile strength, wear resistance and processability, keeping compatibility of both good fuel efficiency and high gripping property, and a production method thereof. What is characterized in the composition is that the composition is comprised of 100 parts by weight of a diene rubber having a molecular weight distribution expressed in terms of the ratio of the weight-average molecular weight to the number-average molecular weight of 1.1 to 30, 20 to 200 parts by weight of silica and a cationic polymer, and that a toluene-insoluble rubber content per gram of the silica within the range from 0.2 to 1 g, and diene cross-linked rubber thereof.

Abstract: Disclosed are silica-filled rubber granules comprised of a cocoagulation product of rubber and silica, which are extremely less powdery and excellent in handling and kneading, as well as an industrially advantageous process for producing same. The silica-filled rubber granules of the present invention are dried granules of a cocoagulation product of rubber and silica particles, which are characterized in that an average particle diameter (D50) in terms of the sieve analysis is 300˜3000 ?m and the weight ratio of the granules within the range of D50±(D50×0.5) is at least 50% by weight. The silica-filled rubber granules are produced by supplying a cake of a cocoagulation product of silica and rubber having a water content of 40˜80% by weight to a drier provided with an indirect-heating type container having stirring wing blades, and then drying the cake while stirring it with the stirring wing blade.

Abstract: A conjugated diene rubber obtained by a process wherein active conjugated diene polymer chains each having an active metal at a polymer chain terminal, which have been obtained by polymerizing a conjugated diene monomer alone, or a conjugated diene monomer and an aromatic vinyl monomer with the aid of an organic active metal in an inert solvent, are allowed to react with a specific polyorganosiloxane capable of reacting with the active metal bonded to the polymer chain terminal. The conjugated diene rubber contains at least 5% by weight of a structure comprising at least three conjugated diene polymer chains bonded through a polyorganosiloxane. The conjugated diene rubber gives, when silica is incorporated therein, a rubber composition having good processability and giving a crosslinked rubber having reduced heat build-up, good wet grip performance and good abrasion resistance.

Abstract: A silica-containing rubber composition produced by filtering slurry of silica-containing rubber crumbs obtained by co-coagulating a mixture of rubber latex and silica to give a moisture content of 80 wt % or less, dehydrating by a dehydrator having a compression function, then, drying. According to the present invention, a silica-containing rubber composition with improved silica dispersibility can be provided.

Abstract: An oil-extended rubber comprising a conjugated diene rubber having a specific amount of isoprene units, and an extender oil incorporated therein, characterized in that the rubber is obtained by polymerizing a monomer mixture comprising 1,3-butadiene and an aromatic vinyl monomer with the aid of an organic active metal as an initiator in a hydrocarbon medium; subsequently adding isoprene to continue polymerization, then; reacting the resulting polymer having an activated terminal with a coupling agent. A rubber composition comprising the oil-extended rubber is suitable for tread of tire having a low fuel consumption.

Abstract: A diene rubber (A) having a weight average molecular weight (Mw) of 100,000 to 3,000,000, an Mw/number average molecular weight (Mn) ratio of 1.30 to 2.50, and an Mw/peak top molecular weight (Mp) ratio 0.70 to 1.30. A rubber composition comprising the diene rubber (A) and a diene rubber (B) having an Mw of 2,000 to 90,0000 and/or an oil extender for rubber has good processability and can give a rubber vulcanizate having high tensile strength and good abrasion resistance. The diene rubber (A) is produced by conducting a living polymerization of diene monomer in a hydrocarbon solvent; adding a polymerization stopper to a polymerization mixture at a conversion of 5 to 98% to deactivate 10 to 90% by mole of active terminals present as of the initiation of polymerization; and finally adding a polymerization stopper to completely terminate the polymerization reaction.

Abstract: A diene rubber (A) having a weight average molecular weight (Mw) of 100,000 to 3,000,000, an Mw/number average molecular weight (Mn) ratio of 1.30 to 2.50, and an Mw/peak top molecular weight (Mp) ratio 0.70 to 1.30. A rubber composition comprising the diene rubber (A) and a diene rubber (B) having an Mw of 2,000 to 90,0000 and/or an oil extender for rubber has good processability and can give a rubber vulcanizate having high tensile strength and good abrasion resistance. The diene rubber (A) is produced by conducting a living polymerization of diene monomer in a hydrocarbon solvent; adding a polymerization stopper to a polymerization mixture at a conversion of 5 to 98% to deactivate 10 to 90% by mole of active terminals present as of the initiation of polymerization; and finally adding a polymerization stopper to completely terminate the polymerization reaction.

Abstract: An oil-extended rubber comprising a conjugated diene rubber having a specific amount of isoprene units, and an extender oil incorporated therein, characterized in that the rubber is obtained by polymerizing a monomer mixture comprising 1,3-butadiene and an aromatic vinyl monomer with the aid of an organic active metal as an initiator in a hydrocarbon medium; subsequently adding isoprene to continue polymerization, then; reacting the resulting polymer having an activated terminal with a coupling agent. A rubber composition comprising the oil-extended rubber is suitable for tread of tire having a low fuel consumption.

Abstract: An oil-extended rubber comprising 100 weight parts of a rubber ingredient comprising a conjugated diene rubber wherein the ratio (Mw/Mn) of weight average molecular weight (Mw) to number average molecular weight (Mn) is in the range of 1.2 to 2.2, and the conjugated diene monomer units have a vinyl bond unit content of at least 20%, and 5-100 weight parts of a process oil having a total acid value of not larger than 1.0 mgKOH/g, a pour point of not higher than 50° C. and an aromatic carbon content of at least 20%. A rubber composition comprising 100 weight parts of the above-mentioned rubber ingredients, 5-100 weight parts of the process oil and 10-200 weight parts of a reinforcing agent. This rubber composition gives a crosslinked article having high tensile strength, high abrasion resistance and reduced heat build-up, and is useful, for example, as an automobile tire material.